#ifndef NOD
#define NOD
class Nod{/*nodul din arborele expresiei functiei*/
	protected:
		Nod *fStang, *fDrept;/*fii stang si drept*/
		static long double x;/*valoarea punctului in care se face calculul
					expresiei*/
	public:
		Nod();
		~Nod();
		/*metodele virtuale*/
		virtual long double calcul() = 0;
		virtual char *derivare() = 0;
		virtual long double calculDerivata() = 0;
		virtual char *toString() = 0;
		Nod *getFStang();
		void setFStang(Nod *x);
		Nod *getFDrept();
		void setFDrept(Nod *x);
		static void setX(long double X);
		static long double getX();
};
#endif
